I have branded as a "Jammer". I was wondering whether I fit the profile of one. So far, I am safe.

I tend to agree with Dan. Aiki is about seeking the path of least resistance (changing directions) rather than going against the resistance. I get irritated by nage who jerks or bounces me around instead of doing a free flowing technique on me. To avoid injury, the jerking and bouncing cause me to stiffen up and assume a defensive stance. Perhaps this is jamming as far as they are concerned.